John 13:27

And after the sop Satan entered into him. Then said Jesus unto him, That thou doest, do quickly.

Ver. 27. Satan entered into him] Had gotten more full possession of him. Let them that depart the public assemblies ere all be done, as Judas did, take heed they meet not the devil at the door. The fourth Council of Carthage excommunicated such, and so delivered them up to Satan, which is a grievous punishment; for then they lie open to all wickedness, as Ananias, whose heart Satan had filled from corner to corner. Luther when he had read certain letters sent to him from Vitus Theodorus, fetched a deep sigh, and said, Heu quam furit Satan, et impellit securos homines ad horrenda flagitia, quae corpus et animum perdunt! Oh how the devil rageth and driveth on secure persons to horrible and damnable wickedness! That which moved Luther to say so, was a sad relation made in that letter, of a certain widow, who being with child by a young scholar, could not have her child baptized unless she would tell the priest who was the child's father; whereat she being grievously vexed, first killed her child and then hanged herself. Which when the scholar heard of, he likewise stabbed himself to death. The priest understanding what tragedies had followed upon his refusing to baptize the child, hanged himself also. Now, who can doubt but all this was done by the instigation of the devil? Men usually defy him and spit at his name; but they spit not low enough, they spit him out of their mouths, but not out of their hearts; there he plays Rex, and so long cares no more for their cursing of him than he doth for holy water.

That thou doest, do quickly] This is no command, but a prediction by way of detestation; like as when God said to Balaam, Go, for I know thou wilt go after the wages of wickedness. Some note here that, even to Judas, Christ saith, "That thou doest, do quickly," so odious is dulness unto him. (Ward's Serm.)